TRT 4.0 sampleUffSSD int8 calibration failing

I was able to get the calibration to succeed by increasing the number of images used from 500 to 7500. Answer found here https://devtalk.nvidia.com/default/topic/1036911/tensorrt/cannot-run-sampleuffssd-for-int8-inference-calibration-failed-/post/5281105/#5281105