If one is concerned about the present tax distribution and burden, it probably makes the most sense to compare the current situation to history.
I think Table 8 [link|http://www.taxfoundation.org/publications/show/250.html|here] is enlightening:
Table 8. Average Tax Rate, 1980-2005 (% of AGI paid in income taxes):
Year\tTotal\tTop 1%\tTop 2-5%\tTop 5%\tTop 6-10%\tTop 10%\tTop 11-25%\tTop 25%\tTop 26-50%\tTop 50%\tBottom 50%
1980\t15.31%\t34.47%\t21.71%\t26.85%\t17.13%\t23.49%\t14.80%\t19.72%\t11.91%\t17.29%\t6.10%
1981\t15.76%\t33.37%\t22.08%\t26.59%\t18.16%\t23.64%\t15.53%\t20.11%\t12.48%\t17.73%\t6.62%
1982\t14.72%\t31.43%\t20.44%\t25.05%\t16.61%\t22.17%\t14.35%\t18.79%\t11.63%\t16.57%\t6.10%
1983\t13.79%\t30.18%\t18.77%\t23.64%\t15.54%\t20.91%\t13.20%\t17.62%\t10.76%\t15.52%\t5.66%
1984\t13.68%\t29.92%\t18.41%\t23.42%\t15.57%\t20.81%\t12.90%\t17.47%\t10.48%\t15.35%\t5.77%
1985\t13.73%\t29.86%\t18.44%\t23.50%\t15.69%\t20.93%\t12.83%\t17.55%\t10.41%\t15.41%\t5.70%
1986\t14.54%\t33.13%\t19.10%\t25.68%\t15.99%\t22.64%\t12.97%\t18.72%\t10.48%\t16.32%\t5.63%
Tax Reform Act of 1986 changed the definition of AGI, so data above and below this line not strictly comparable\t\t\t\t\t\t\t\t\t\t\t
1987\t13.12%\t26.41%\t18.13%\t22.10%\t14.43%\t19.77%\t11.71%\t16.61%\t9.45%\t14.60%\t5.09%
1988\t13.21%\t24.04%\t17.85%\t21.14%\t14.07%\t19.18%\t11.82%\t16.47%\t9.60%\t14.64%\t5.06%
1989\t13.12%\t23.34%\t17.97%\t20.71%\t13.93%\t18.77%\t12.08%\t16.27%\t9.77%\t14.53%\t5.11%
1990\t12.95%\t23.25%\t17.60%\t20.46%\t13.63%\t18.50%\t12.01%\t16.06%\t9.73%\t14.36%\t5.01%
1991\t12.75%\t24.37%\t17.10%\t20.62%\t13.96%\t18.63%\t11.57%\t15.93%\t9.55%\t14.20%\t4.62%
1992\t12.94%\t25.05%\t17.21%\t21.19%\t13.99%\t19.13%\t11.39%\t16.25%\t9.42%\t14.44%\t4.39%
1993\t13.32%\t28.01%\t17.48%\t22.71%\t14.01%\t20.20%\t11.40%\t16.90%\t9.37%\t14.90%\t4.29%
1994\t13.50%\t28.23%\t17.93%\t23.04%\t14.20%\t20.48%\t11.57%\t17.15%\t9.42%\t15.11%\t4.32%
1995\t13.86%\t28.73%\t18.19%\t23.53%\t14.46%\t20.97%\t11.71%\t17.58%\t9.43%\t15.47%\t4.39%
1996\t14.34%\t28.87%\t18.68%\t24.07%\t14.74%\t21.55%\t11.86%\t18.12%\t9.53%\t15.96%\t4.40%
1997\t14.48%\t27.64%\t18.78%\t23.62%\t14.87%\t21.36%\t12.04%\t18.18%\t9.63%\t16.09%\t4.48%
1998\t14.42%\t27.12%\t19.14%\t23.63%\t14.79%\t21.42%\t11.63%\t18.16%\t9.12%\t16.00%\t4.44%
1999\t14.85%\t27.53%\t19.68%\t24.18%\t15.06%\t21.98%\t11.76%\t18.66%\t9.12%\t16.43%\t4.48%
2000\t15.26%\t27.45%\t20.07%\t24.42%\t15.48%\t22.34%\t12.04%\t19.09%\t9.28%\t16.86%\t4.60%
2001\t14.23%\t27.50%\t19.12%\t23.68%\t14.89%\t21.41%\t11.58%\t18.08%\t8.91%\t15.85%\t4.09%
2002\t13.03%\t27.25%\t18.15%\t22.95%\t13.87%\t20.51%\t10.47%\t16.99%\t7.67%\t14.66%\t3.21%
2003\t11.90%\t24.31%\t16.58%\t20.74%\t12.22%\t18.49%\t9.54%\t15.38%\t7.12%\t13.35%\t2.95%
2004\t12.10%\t23.49%\t16.95%\t20.67%\t12.28%\t18.60%\t9.26%\t15.53%\t7.01%\t13.51%\t2.97%
2005\t12.45%\t23.13%\t17.36%\t20.78%\t12.37%\t18.84%\t9.27%\t15.86%\t6.93%\t13.84%\t2.98%
IOW, the percentage of AGI paid by the top 1% has dropped significantly more over the recent years compared to the percentages paid by the other groups. (E.g. compare 2001 to 2005 - -4.4% for top 1% versus -2% for top 50%.)
Cheers,
Scott.
(Who doesn't accept that FICA vs general taxes is apples and oranges, btw...)