another problem with index

[Daniel Silva]

Hi,
I'm having a litle problem with one index

CREATE TABLE `date` (
`data_Id` int(10) unsigned NOT NULL,
`date` date NOT NULL,
PRIMARY KEY (`data_Id`),
KEY `date` (`date`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;

CREATE TABLE `data` (
`data_Id` int(10) unsigned NOT NULL,
`rop` tinyint(3) unsigned NOT NULL,
`data` int(10) unsigned DEFAULT NULL,
PRIMARY KEY (`data_Id`,`rop`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;

explain
SELECT
straight_join
*
FROM
date re
join data r
using(data_id)
WHERE rop >=1 and rop <=4
and date='2011-07-05';

this returns:
+----+-------------+-------+------+---------------+---------+---------+-----------------------------------+--------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+------+---------------+---------+---------+-----------------------------------+--------+-------------+
| 1 | SIMPLE | re | ref | PRIMARY,date | date | 3 | const | 348038 | |
| 1 | SIMPLE | r | ref | PRIMARY | PRIMARY | 4 | orange_es_stats_3g_rop.re.data_Id | 93 | Using where |
+----+-------------+-------+------+---------------+---------+---------+-----------------------------------+--------+-------------+

I was expecting the 93 to be a 4, because the condition rop >=1 and rop <=4.
Each data_id has a maximum of 96 rops.

I'm missing something?
Thx