This could be a loaded question. There is a comment(+153) in /r/india claiming that "for 200 years between 1700 to 1900, every single dollar of improvement in the Indian economy was shipped out to Britain via the process of colonialism.".
I am trying to validate the claims made in the following comment. Please ignore any propaganda in it.
When you say India's GDP share went down, neocolonialists/colonial apologists and their pet brown sepoys readily defend it by claiming it was purely due to the West's growth during industrial revolution and had nothing to do with colonial exploitation in India. That's complete bullshit. I'll give you another interesting statistic that gives you a much clearer understanding of issues.
India's population in 1700 was 127 million. In 1900, it was 271 million. Source
India's GDP in 1700 was $90 billion. India's GDP in 1900 was $192 billion, all figures in 1990 USD. Source: http://en.wikipedia.org/wiki/List_of_regions_by_past_GDP_(PPP)
So India's GDP per capita in 1700 was $708. In 1900 it was $708.
India's GDP growth (adjusted to population) from 1700 to 1900 was a grand total of 0%.
But wait, what does that actually mean? Does that mean that there was no improvement in production between 1700 to 1900? Does that mean there was no improvement in technology between 1700 to 1900? Does that mean that trade did not increase for 200 years? Clearly not as improvements in production, technology, trade networks, etc are a natural process over time, especially over such a long period of time. But the growth was 0%. FFS, the British and their intellectual Sepoy chamchas love reminding us how the British gifted us the industrial revolution, albeit a tad late, in the mid to late 19th century. So how was the growth 0%?
The West's industrial revolution took place at a 3% GDP growth and 1.1% capita income growth after 1820. So, if we assume a mediocre growth of 0.25% per annum in India, the per capita GDP growth should have been 65% over 200 years. Even if we assume a very poor growth rate of 0.1% per annum in India, the per capita GDP should have grown by 22% over 200 years. But the growth was 0%.
So what does this mean? The figures mean, that for 200 years between 1700 to 1900, every single dollar of improvement in the Indian economy was shipped out to Britain via the process of colonialism. First by the East India Company and later by the British government itself since 1857 onwards.
So remember this, when our dearly beloved White colonial masters and their brown sepoys tell us how grateful we should be to colonialism for giving us the Industrial revolution in the mid to late 1800s, how grateful we should be for the fucking railway system, how grateful we should be for white people for teaching us how to be civilized and modern, how India owes everything it has to the limey British, remember this.
Remember that for 200 years, every single dollar in progress made by every single Indian was stolen and taken to Britain.
The next time someone tells you about the benefits of colonialism, give them one tight slap.
EDIT: Angus Maddison actually estimates that GDP per capita in India had a NEGATIVE GROWTH between 1700 and 1870. Source: http://en.wikipedia.org/wiki/List_of_regions_by_past_GDP_(PPP)_per_capita
^Note: ^I ^do ^not ^want ^to ^break ^any ^rules. ^If ^I ^did ^please ^help ^me ^in ^asking ^the ^question ^in ^the ^right ^way.
I can't verify the statistics, but I can offer some more general explanation and clear up some of the difficulties posed by the immature interpretation.
The first flaw is the concept of an 'industrial revolution' itself. India remained a largely agricultural nation throughout British rule with elements of feudalism still present in many parts of the country, the capitalist relations only developing on a larger scale near the end of the Raj (this is not a coincidence. the contradictions in Indian society grew as capitalism developed).
Second is the idea that India's 'industrial revolution' would take a path similar to that in England. The development of capitalist relations in India took place under imperialism, which radically alters the character of development. At the beginning of the 18th Century there was a flourishing handicraft industry - producing textiles, silk, etc. - in India, comparable to many smaller powers (e.g. Germany) in Europe. What we don't see, however, is rapid industrialisation as in England or other colonial powers later on. This is due to the introduction of English goods into the marketplace, which also caused the destruction of Indian handicraft. Edmund Burke stated that East India Co. was the reason for the degradation of the Indian economy. Not only were the English goods cheaper, the Rupee was being devalued because it was on the silver standard, which further exacerbated the imbalance in trade. In return India became a critical source of raw material to English industry.
The predatory relationship was more complicated than simple 'stealing' as presented in the post, though heavy taxation did factor into limiting growth. The national liberation movement included the Indian capitalist class, they were completely aware that the imperialist relations were barring them from further development. Mere economics don't really capture the true nature of colonialism, which was harsh and caused a great deal of suffering. The dozens of famines, Jallianwallah Bagh, etc.. Most of the famine conditions have been traced to British policy by Amartya Sen. The truth is that the Raj in India cannot be justified by any sensible person, though (without the imperialist excesses) many of the same policies can be seen today in a more subtle form.