Note:
Subversion up to 1.8.16 (inclusive) have security issues.

Subversion 1.8.1 installer for Apache httpd 2.2.x and 2.4.x
Windows installer: Setup-Subversion-1.8.1-1.msi
README file: README.txt
Subversion 1.8.1 for Apache httpd 2.2.x
Subversion book as Windows help file: svn-book.chm
Windows binaries: svn-win32-1.8.1.zip
Development libs and doc: svn-win32-1.8.1_dev.zip
Debug symbols: svn-win32-1.8.1_pdb.zip
JavaHL bindings: svn-win32-1.8.1_javahl.zip
Perl 5.9 bindings: svn-win32-1.8.1_pl.zip
Python 2.6 bindings: svn-win32-1.8.1_py26.zip
Python 2.7 bindings: svn-win32-1.8.1_py27.zip
Ruby bindings: svn-win32-1.8.1_rb.zip
README file: README.txt
Subversion 1.8.1 for Apache httpd 2.4.x
Windows binaries: svn-win32-1.8.1-ap24.zip
Development libs and doc: svn-win32-1.8.1-ap24_dev.zip
Debug symbols: svn-win32-1.8.1-ap24_pdb.zip
JavaHL bindings: svn-win32-1.8.1-ap24_javahl.zip
Perl 5.9 bindings: svn-win32-1.8.1-ap24_pl.zip
Python 2.6 bindings: svn-win32-1.8.1-ap24_py26.zip
Python 2.7 bindings: svn-win32-1.8.1-ap24_py27.zip
Ruby bindings: svn-win32-1.8.1-ap24_rb.zip
README file: README.txt