With exponentially-growing things, 1% done is halfway there. From a Ray Kurzweil article:
"Kurzweil noted that many people don’t understand the basic math of exponential trends. When the Human Genome project had sequenced only 1% of the genome after seven years of costly labor, many cited the lack of progress as evidence that the project was doomed. Yet the sequencing project was riding an exponential trend in the performance DNA sequencing methods. Instead of taking another seven years to sequence a second 1%, they reached it after only one year. Then they reached 4% in about another year, then 8%, 16%, and so on. It took about as much time to sequence the last 99% as it took to sequence the first 1%. That’s the nature of exponential trends — they seem to start glacially slowly but finish lightning fast."
"Kurzweil noted that many people don’t understand the basic math of exponential trends. When the Human Genome project had sequenced only 1% of the genome after seven years of costly labor, many cited the lack of progress as evidence that the project was doomed. Yet the sequencing project was riding an exponential trend in the performance DNA sequencing methods. Instead of taking another seven years to sequence a second 1%, they reached it after only one year. Then they reached 4% in about another year, then 8%, 16%, and so on. It took about as much time to sequence the last 99% as it took to sequence the first 1%. That’s the nature of exponential trends — they seem to start glacially slowly but finish lightning fast."