The Kashmiri Pandits, the only Hindus of the Kashmir valley, who had stably constituted approximately 4 to 5% of the population of the valley during Dogra rule (1846–1947), and 20% of whom had left the Kashmir valley by 1950, began to leave in much greater numbers in the 1990s. According to a number of authors, approximately 100,000 of the total Kashmiri Pandit population of 140,000 left the valley during that decade.  Other authors have suggested a higher figure for the exodus, ranging from the entire population of over 150 to 190 thousand (1.5 to 190,000) of a total Pandit population of 200 thousand (200,000) to a number as high as 300 thousand (300,000).
Question: How many years after the Dogra rule did 20% of the Kashmiri Pandits leave?
Answer: 3