Did 20% of the Soviet Population use a Latin script in 1935?
The literacy campaigns in the Soviet Union between 1917 and 1940 taught many people to read. Many people who did not speak Russian had no alphabet for their language, so appropriate alphabets were devised for these populations. Before 1940, most of these new alphabets used Latin letters.
This non-peer reviewed article about Soviet language policy says that about 36 million people used Latin letters in 1935. Is this accurate, or is it an exaggerated claim? Another website says the Soviet population was 170 million, corresponding with about 20%.
Was 20% of the Soviet Population using a non-Cyrillic script in 1935? Is that possible?
You make the wrong conclusion from what the paper says:
The next step in alphabet reform came at the 1926 Baku (Azerbaijan) Turkological Congress, which proposed the adoption of the Latin script for all Turkic languages in the USSR. By 1930, the Arabic script had been replaced by the Birlashdirilmish yangi Turk alifbesi (New Unified Turkic alphabet). By 1935, a total of seventy Soviet languages (not all of them Turkic), representing 36 million people, were being written in the Latin alphabet, modified by diacritics where needed. Although this obviously slowed down the literacy campaign, it also came at a time when there was a new push to eliminate illiteracy.
Indeed, in 1930 they introduced Latin alphabet for Turkish languages, but then in 1935 switched to Cyrillic. However most of the population of the area affected by these reforms was illiterate both in 1930 and in 1935. So it is wrong to conclude that "36 million people used Latin alphabet".
To address some comments: Latin alphabet was never used in Ukraine or Belorussia (in 20th century), while Moldova and Baltic republics were not parts of the Soviet Union until 1940. Latin alphabet was introduced for short period in Asian republics.
Kazakhstan used a Latin alphabet until the Soviets forced them to use Cyrillic, the same was probably true in other central Asian countries. So it is quite likely to be true, yes.
Source: I used to live in Kazakhstan.