Tracking tax avoidance

" U.S. Lawmakers Slam Caterpillar Over Tax Avoidance". That headline last month in one of our drab but professional  trade mags brought a sardonic smile to my face as I imagined a black-windowed Hummer careering around Capitol Hill jam-packed with Senators. At the vehicle's wheel was Carl Levin who suddenly screamed "Ya-hoo" ,or whatever 80-year-old  Americans from Michigan scream when…