The following is a graphical representation of the total number of books in the Bible with their corresponding total number of chapters:
The following is a graphical representation of occurrences of words like "sin", "blood", and "atonement" used in the Bible respective of the books. Graphically we can see that during the Old Testament times, there was more blood of the animals shed, according to the law of Moses for the atonement of people's sins during the Levitical priesthood.
Whereas in the New Testament, the usage of the word "blood" reduces in the Bible because, Jesus shed His precious Blood once for all, as an eternal sacrifice, and thereby establishing the new covenant of "Grace" (Hebrews 10:8-10) according to the Melchizedek priesthood.
It is interesting to note that the usage of the word "atonement" in the Bible also reduces, and the usage of the word "grace" is more often used in the New Testament compared with the Old Testament, meaning to say that we are not saved by our works, but by "Grace through Faith" (Ephesians 2:8). This is more the evidence that all scripture is God breathed.
We can observe from the graph, that there is a reduction of sin between the letters of Apostle Paul to the Romans till Philemon, which were the letters written to the different Churches and its believers in Christ. We see a reduction in sin compared to the Old Testament because, Apostle Paul preached the new covenant of Grace, and made people conscious of their abundant forgiveness by the Blood of Christ, rather than making them conscious of their sins. The believers in the Church were conscious of their righteousness in our Lord Jesus, and hence "sin did not have dominion" over the believers (Romans 6:14).