Dictionary in for loop not working as I expected to be

This happens because you only have 22 unique values in bx3 List.

Specifically you have these values repeated:

'Consumer Services': 6,
 'Materials': 103,
 'Health Care Equipment & Services': 15,
 'Commercial & Professional Services': 8,
 'Capital Goods': 13,
 'Software & Services': 12,
 'Diversified Financials': 7,
 'Energy': 10,
 'Transportation': 1,
 'Utilities': 2,
 'Retailing': 5,
 'Real Estate': 5,
 'Technology Hardware & Equipment': 3,
 'Pharmaceuticals, Biotechnology & Life Sciences': 10,
 'Household & Personal Products': 1,
 'Food & Staples Retailing': 1,
 'Food, Beverage & Tobacco': 4,
 'Media & Entertainment': 6,
 'Consumer Durables & Apparel': 1,
 'Banks': 1,
 'Semiconductors & Semiconductor Equipment': 1,
 'Automobiles & Components': 2