In 1860, there were 20,000 professionals in Russia and 85,000 by 1900. Originally composed of educated nobles, the intelligentsia became dominated by raznochintsy (class-less people) after 1861. In 1833, 78.9 per cent of secondary-school students were children of nobles and bureaucrats, by 1885 they were 49.1 per cent of such students. The proportion of commoners increased from 19.0 to 43.8 per cent, and the remaining percentage were the children of priests. In fear of an educated proletariat, Tsar Nicholas I of Russia limited the number of university students to 3,000 per year, yet there were 25,000 students, by 1894. Similarly the number of periodicals increased from 15 in 1855 to 140 periodical publications in 1885. The "third element" were professionals hired by zemstva. By 1900, there were 47,000 of them, most were liberal radicals.
Question: How many more periodicals publications were in 1885 than 1855?
Answer: 30