Yes, polls indicate that most people who commit their lives to Jesus Christ do so before they are 25 -- and often much younger. It was true in my own life (I was around 17) and continues to be true in the festivals my son Franklin holds around the world.
It's also true that comparatively few older people turn to God, even though (as you point out) it would be logical for them to do so. Why is this? The main reason is because the more we shut God out of our lives, the more calloused and insensitive our hearts become -- and the harder it is for us to hear God's call and respond to it. Just as most of us get deafer and deafer as we grow old, so our hearts grow "deafer and deafer" to God. This is why the Bible says, "Today, if you hear his voice, do not harden your hearts" (Hebrews 4:7).
But God still loves us, and even in the last hours of life, He still yearns for us to turn to Christ and trust Him for our salvation. And when we do, He promises to forgive us and save us. We'll have missed a lifetime of joy, but ahead of us is still heaven.
The two criminals who were crucified with Jesus had only hours to live, but Jesus promised the one who begged to be saved, "I tell you the truth, today you will be with me in paradise" (Luke 23:43).