When preforming a high-throughput RNA sequencing (with human samples), how many of the 3 billion base pairs of DNA  will get covered after alignment and quality control?

In other words - how much of the genome can theoretically be reproduced from the RNA-seq?

I'm looking for even just a rough estimate, but if it helps, the samples that I'm interested in are from human brains, expressing ~16,000 genes, of which ~13,000 are protein coding. 

I couldn't find an answer by googling, and will appreciate any help.
I have looked at a high-quality brain sample that I had worked on. 

    samtools depth -a data.bam | awk ' $3>0 { count += 1  } END { print (count/NR) }'

It appears that the genome is covered at about `7.5%` rate (command took 20 minutes to compute that) 

It is true that the larger fraction of a genome may be observed transcribed into RNA, but those would not be picked up by a typical RNA-Seq experiment.