This task involves annotating the answer type to a given question that involve some kind of complex reasoning (including numerical reasoning). Note that the questions require looking at more than one part of the passage to answer. There are 3 possible answer types (i) spans, (ii) numbers and (iii) dates. If the answer can be found in the passage, label it as "span". If the answer is a number, label as "number". Similarly, label "date" if you think the answer to the given question is a date.

Passage: In the early 1860s, Europe and the United States pursued completely different trade policies. The 1860s were a period of growing protectionism in the United States, while the European free trade phase lasted from 1860 to 1892. The tariff average rate on imports of manufactured goods was in 1875 from 40% to 50% in the United States against 9% to 12% in continental Europe at the height of free trade. Between 1850 and 1870 the annual growth rate of GNP per capita was 1.8%, 2.1% between 1870 and 1890 and 2% between 1890 and 1910; the best twenty years of economic growth were therefore those of the most protectionist period (between 1870 and 1890), while European countries were following a free trade policy.
Question: Which year span was the annual growth rate of GNP per capita the highest percentage, 1850-1870 or 1870-1890?
span