Apple remained the top smartphone manufacturer in the U.S. in the third quarter, according to the latest data from Nielsen. Based on the data, the iPhone accounted for 28 percent of all smartphones in the U.S., while phones based on Google’s Android OS collectively represent 43 percent of the smartphone market. RIM’s BlackBerry accounted for 18 percent, Windows Phone for seven percent, and all other operating systems for four percent. Overall, smartphones now represent 43 percent of the overall U.S. cellphone market, and a “vast majority” of those under the age of 44 now own smartphones, with 62 percent of mobile adults aged 25-34 report owning one of the devices.