Question to the Home Office:

To ask Her Majesty's Government what percentage of asylum appeals were successful in (1) 1990, (2) 1995, (3) 2000, (4) 2005, (5) 2010, and (6) 2015.

The Home Office publishes data on the number of asylum appeals received and determined, broken down by outcome, in the quarterly Immigration Statistics release. The latest figures are available at the following link:
https://www.gov.uk/government/statistics/immigration-statistics-july-to-september-2017

Table as_14 in the asylum tables (volume 4) contains annual breakdowns of the number of appeals between 2007 and 2016. The table is attached for further reference.

Data prior to 2007 can be found in the national archives:
http://webarchive.nationalarchives.gov.uk/20110218143229/http://rds.homeoffice.gov.uk/rds/hosbarchive.html

Data for 1990 are not available as the Asylum and Immigration Appeals Act 1993 came into force on 26 July 1993.