digital integrator/ pulse counter

Here's the problem and thanks for any help in advance! I am counting pulses from a laser with an 80MHz rep rate. Not every pulse is detected, but when they are it generates a TTL pulse (5ns). The problem is the integrator in my PC only has bandwidth to 5MHz, but most of the signal in these 5ns pulses is way higher frequency so the computer reports a low voltage even though there's plenty of signal. What I need is a integrator that can count the number of pulses and output an analog voltage proportional to the number of counts it received. E.g. if every laser pulse was detected there would be 80 counts per 1us so it would output Vmax, but if only 40 were detected in that same 1us it would ouput an analog voltage half of Vmax. This way the signal will have lower frequency components and the PC will accurately interpret it. I need help selecting the IC chip that would best perform this signal process! Suggestions?