Thanks to low mortgage rates, the government share of the home purchase market rose in June, according to new numbers compiled from the Campbell/Inside Mortgage HousingPulse Tracking Survey. But the latest survey also highlighted several factors that are likely to put downward pressure on home prices in the balance of this year. Mortgage rates have been falling for the past several months, dipping to below 4.5 percent in June for 30-year fixed-rate mortgages financed through Fannie Mae, Freddie Mac and FHA, Inside Mortgage Finance’s weekly sampling of rates reveals. This has helped ... [contains one graph]