Read this and answer the question. If the question is unanswerable, say "unanswerable".

The majority of British Jews live in London, with significant Jewish communities in Stamford Hill, Stanmore, Golders Green, Finchley, Hampstead, Hendon and Edgware in North London. Bevis Marks Synagogue in the City of London is affiliated to London's historic Sephardic Jewish community. It is the only synagogue in Europe which has held regular services continuously for over 300 years. Stanmore and Canons Park Synagogue has the largest membership of any single Orthodox synagogue in the whole of Europe, overtaking Ilford synagogue (also in London) in 1998. The community set up the London Jewish Forum in 2006 in response to the growing significance of devolved London Government.

London's Stanmore and Canons Park Synagogue passed London's Ilford Synagogue in terms of membership in what year?
1998