Note that three of the four individuals noted in the Acknowledgments are skeptics (Christy, Knappenberger, and of course, Michaels).
Kind of old, but has some numbers, notably:
" The sensitivity of climate to solar radiation changes, as defined earlier, is not well known. A conservative estimate is that a 0.1 percent change in solar total radiation will bring about a temperature response of 0.06 to 0.2°C, providing the change persists long enough for the climate system to adjust. This could take ten to 100 years."
Using just this number, let's say that solar radiation increased 0.5% in the 20th century. The maximum expected temperature response would be 1 deg. C (minimum 0.3 C). The observed increase over the entire 20th century was 0.6 C, which falls in this range.
However, over the past 25 years, the global temperature increase has been 0.8 C. The decadal maximum solar radiation increase is 3 x 0.05% = 0.15% -- from the numbers above, this could result in a maximum 0.3 C increase due to solar radiation. Observations indicate much more than that. As from this figure, the late 20th century temperature rise (into the 21st) doesn't appear to be attributable to solar forcing. And studies of the entire 20th century have stated that about 0.2 C of the 0.6 C could be attributed to solar forcing, with a more significant solar contribution in the early part of the century.
It's clear from multiple indicators that solar variability has become one of the bastions of scientifically-minded climate change skeptics. I view that position as assailable. (Which you might have guessed.)