Lobbying Statistics: A Growing Multi-Billion Dollar Business

We always knew lobbying is big. But how big is it exactly? We know corporates spend a lot on this activity, but can this number be used as a measure of calculating, on a percentage basis, bias in decisions? We spotted this today:

" By 2011, one estimate of overall lobbying spending nationally was $30+ billion dollars.
An estimate of lobbying expenses in the federal arena was $3.5 billion in 2010, while it had been only $1.4 billion in 1998."

Statistics Source: Wikipedia