stat: fix typo

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/stat.c b/stat.c
index 40e3b1b..7e3b979 100644
--- a/stat.c
+++ b/stat.c
@@ -443,7 +443,7 @@
 		double p_of_agg = 100.0;
 		const char *bw_str = "KB";
 
-		if (rs->agg[dir]) {
+		if (rs->agg[ddir]) {
 			p_of_agg = mean * 100 / (double) rs->agg[ddir];
 			if (p_of_agg > 100.0)
 				p_of_agg = 100.0;