There is no increase in ‘illegal’ Israel settlements in the West Bank
Neither is it true that there has been a “significant increase” in these settlements since Oslo. No new officially-approved settlements have been built since 1998. All construction since then has taken place within the boundaries of existing towns and villages.
As for the proportion of the area of Judea-Samaria comprising the Jewish towns, this has been variously estimated as 1.7% (B’Tselem), 1.36% (Peace Now) and 1.1% (senior Palestinian negotiator Saeb Erekat in 2011, on the basis of aerial photography).