MINOR: stats: don't use a monospace font to report numbers

On several browsers, the monospace font used to display numbers in tips
is not much readable. Since the numbers are aligned anyway, there is too
little benefit in using such a font.
diff --git a/src/dumpstats.c b/src/dumpstats.c
index d39da41..937fe7f 100644
--- a/src/dumpstats.c
+++ b/src/dumpstats.c
@@ -3568,7 +3568,7 @@
 	              "table.lgd td.noborder { border-style: none; padding: 2px; white-space: nowrap;}\n"
 	              "table.det { border-collapse: collapse; border-style: none; }\n"
 	              "table.det th { text-align: left; border-width: 0px; padding: 0px 1px 0px 0px; font-style:normal;font-size:11px;font-weight:bold;font-family: sans-serif;}\n"
-	              "table.det td { text-align: right; border-width: 0px; padding: 0px 0px 0px 4px; white-space: nowrap; font-style:normal;font-size:11px;font-weight:normal;font-family: monospace;}\n"
+	              "table.det td { text-align: right; border-width: 0px; padding: 0px 0px 0px 4px; white-space: nowrap; font-style:normal;font-size:11px;font-weight:normal;}\n"
 	              "u {text-decoration:none; border-bottom: 1px dotted black;}\n"
 		      "div.tips {\n"
 		      " display:block;\n"