Interest rates and financial growth

Looking at the relationship between the level of interest rates and the size of the financial sector suggests that relatively high interest rates encourage the growth of the financial sector. The high interest rates allow an inflow of funds which have to be managed.

This can take a panel analysis.

1990 or first available year 2007 or latest available year average interest rate

India 11.9 14.2
Russian Federation 0.8 14.7 8.86
Slovak Republic 14.8 16.9 4.93
Czech Republic 16.9 17.3 3.24
Norway 17.4 17.9 4.59
Poland 10 18.4 8.42
Greece 16.7 19.4
Turkey 11 20.2 17.5
Mexico 20.7 20.3 9.31
Finland 16.2 21.2 3.18
Korea 14.9 21.6 4.67
Spain 17.2 22.1 3.18
South Africa 16.1 22.1 9.12
Portugal 20.2 22.4 3.18
Hungary 14.6 22.6 4.9
Switzerland 16.2 23.6 1.58
Austria 17.7 24.2 3.18
Denmark 21.5 24.7 3.38
Sweden 20.3 24.8 2.91
Brazil 25.4
Canada 22.7 25.6 3.32
Iceland 16.7 26.2 10.63
Japan 20.7 26.7 0.36
Italy 20.1 27.6 3.18
Ireland 16.4 28.1 3.18
Netherlands 20.7 28.3 3.18
New Zealand 25.4 28.3 6.35
OECD total 24.3 28.4
Belgium 22.6 29 3.18
Germany 23 29.2 3.18
Australia 25.2 29.8 5.72
United Kingdom 21.6 31.9 4.54
United States 24.8 33.1 3.2
France 27.1 33.3 3.18
Luxembourg 28.5 47.3 3.18

(file is OECD rates and size of the financial sector)
There is probably a need for some dummy variables to account for the US reserve currency status, UK history and the developments in Ireland and Luxembourg. What other explanatory variables?